The chemical and morphologocal composition of arterial wall change dramatically during plaque development. We have used 830-nm excited confocal Raman microscopy to collect in situ spectra of various chemical and morphological structures. So far, we have examined spectra of internal and external elastic lamina, collagen fibers, foam cells, necrotic core, adventitial lipid, cholesterol crystals, and calcium mineralization. These structures were studied in 35 different coronary artery samples representing different stages of atherosclerosis. Using these lineshapes, we are currently modeling bulk spectra to quantitatively extract the distribution of these structures. This in turn will be used to provide quantitative pathological information.